The need for alternative fuels is greater now than ever before. As a readily available option with a low pollution factor, natural gas is a viable choice. However, currently available natural gas transportation methods, such as pipelines and liquid natural gas (LNG), may prove unsatisfactory and/or uneconomic. This is particularly the case for “stranded” gas reservoirs. In these stranded gas reservoirs, which are often located off-shore, natural gas is present in quantities which typically do not justify capital-intensive infrastructural investment, such as that necessary to build new pipelines and/or liquefaction/regasification facilities. There is, therefore, an attractive business case for CNG, and especially for marine CNG. In CNG applications, whether terrestrial or marine, natural gas is simply compressed for containment and transportation inside appropriate CNG containment systems. In marine CNG applications, the CNG containment systems are provided onboard ships, barges or other water-going vessels. CNG containment systems, water-going vessels for marine CNG and various CNG related technical aspects are described in patent applications: PCT/EP2011/071782; PCT/EP2011/071786; PCT/EP2011/071788; PCT/EP2011/071789; PCT/EP2011/071790; PCT/EP2011/071791; PCT/EP2011/071792; PCT/EP2011/071793; PCT/EP2011/071794; PCT/EP2011/071795; PCT/EP2011/071796; PCT/EP2011/071797; PCT/EP2011/071798; PCT/EP2011/071799; PCT/EP2011/071800; PCT/EP2011/071801; PCT/EP2011/071802; PCT/EP2011/071803; PCT/EP2011/071804; PCT/EP2011/071805; PCT/EP2011/071806; PCT/EP2011/071807; PCT/EP2011/071808; PCT/EP2011/071809; PCT/EP2011/071810; PCT/EP2011/071811; PCT/EP2011/071812; PCT/EP2011/071813; PCT/EP2011/071814; PCT/EP2011/071815; PCT/EP2011/071816; PCT/EP2011/071817; PCT/EP2011/071818; PCT/EP2012/074556; PCT/EP2011/074557; PCT/EP2011/074558; PCT/EP2011/074559; PCT/EP2011/074560; PCT/EP2011/074561; PCT/EP2011/074562; PCT/EP2011/074563; PCT/EP2012/074564; PCT/EP2012/074568; PCT/EP2012/074569; PCT/EP2012/074571; PCT/EP2011/074572; PCT/EP2011/074573; PCT/EP2011/074574; PCT/EP2012/074575; PCT/EP2012/074577; PCT/EP2011/074578; PCT/EP2011/074579; and PCT/EP2012/074580, the content of which is herein fully incorporated by reference.
Storage of natural gas in highly porous materials (also known as adsorbed natural gas or ANG) has already been proposed and studied, but there remain limitations intrinsic with the existing materials used for this purpose. Such materials include the widely described zeolites, metal organic frameworks (MOFs), porous coordination polymers (PCPs) and, in general, metal organic compounds. In existing metal-organic compounds, positively charged metal atoms bound to organic ligands are extremely sensitive to polar substances, such as water, which may contaminate and degrade the operating material during its life-time. Water contamination is also a problem in compounds containing open metal sites, due to the easy deactivation of the porous material. Further, most metal-containing materials achieve a most effective uptake at relatively low pressures. Moreover, uptake measurements in studies are frequently limited to the range below 40 bar. Pressure ranges below 40 bar, or even below 100 bar, are likely to be insufficient, at least in connection with certain CNG storage/transportation projects.
There is also a general desire to store/transport, with respect to the prior art: (a) comparatively more gas per unit of available storage/transportation volume at a given pressure; and/or (b) a same quantity of gas per unit of available storage/transportation volume at a comparatively lower pressure, thereby allowing less material to be used in an associated recipient for storing and/or transporting the gas, e.g. by decreasing a wall thickness of the recipient; and/or (c) a same quantity of gas at a given pressure, using less storage/transportation volume, thereby reducing an overall size of an associated recipient or of the storage/transport system. These objectives, as it will readily be appreciated, are valid for any to-be-stored and/or transported gas, including, but not limited to, CNG. Accordingly, there is a need for a porous material for high pressure storage of gas, such as CNG, compressed CO2, or other compressed gas, that brings forward an improved gas uptake performance, at least at relatively high pressures, compared to the porous materials for high pressure storage of gas described in the prior art.